Composition and sheet material for inhibition of corrosion of metals



(IOMPOSITION AND SHEET MATERIAL FOR INHElTION F CORROSION 0F METALS Murray Senkus, Western Springs, 111., assiguor to Daubert Chemical Company, a corporation of Illinois No Drawing. Application September 15, 1950, Serial No. 185,141

9 Claims. (Cl. 212.5)

- subject to attack by the elements normally existing in i the atmosphere.

In the U. S. patent of Edward A. Schwoegler and Clemens A. Hutter, No. 2,521,311, dated September 5, 1950, eliective metal corrosion inhibiting compositions are disclosed containing organic amides and inorganic metal nitrites. As is disclosed in said patent, a synergistic effect is secured by virtue of the conjoint use of the aforesaid two types of materials.

Among the inorganic nitrites which can be utilized pursuant to the teachings of the aforesaid patent are the alkali metal nitrites, including ammonium nitrite, sodium nitrite, potassium nitrite and lithium nitrite. 0f particular utility are the water-soluble nitrites. Other nitrites can be utilized including those which are soluble in organic solvents and those which are mutually soluble with the organic amides in organic or other solvent media.

As described in the aforementioned patent, among the amides which can be used in combination with the nitrites are the mono-amides, diamides, and polyamides. The term mono-amide is meant to include organic compounds having the general formula RCONI-Iz, where R is an aliphatic group having from 1-25 or more carbon atoms. These include such amides as acetamide, propionamide, N-butyramide, N-valeramide, stearamide, palmitylamide, fatty acid amides and the like. Although less activity results when R is alicyclic, aromatic or mixed aliphatic aromatic, amides of this type can be used. For example, the amide can be benzarnide or aromatic acid amides of the type of benzenesulfonic acid amide, toluenesulfonic acid amide, naphthalenesulfonic acid amide and the like. The most suitable amides are the diamides, which can be represented by the general formula RQNCONRQ, where R can be hydrogen or an organic radical of the type previously described for the monoamide formula. Illustrative of suitable diamides are urea, guanidine, biuret, and the like, or N-substituted ureas and unsymmetrical ureas such as N, N-dibutyl urea, N-butyl urea, N-propyl urea, dimethyl urea, tertiary butyl urea, tertiary amyl urea, ethyl butyl urea and the like. Of particular utility is urea.

As is further described in the foregoing patent, good results are obtained when the aforesaid compounds are utilized in the ratio of one part of the inorganic nitrite to from about 0.05-20 parts of the amides, said parts being by weight, and particularly advantageous results are obtained by the employment of substantially equal parts by weight of the inorganic nitrite and the organic amide.

My invention is based upon the discovery that the functioning of the aforesaid compositions, in relation to the inhibition of corrosion of ferrous objects, is substantially improved by the incorporation therein or conjoint use therewith of salts of benzoic acid. The action of the salts of benzoic acid appears to synergize the activity of 2,739,370 Patented Mar. 27, 1956 the organic amide-inorganic nitrite compositions so as to bring about a marked enhancement of the corrosion inhibiting properties of the latter compositions.

Among the various salts of benzoic acid which can be utilized in the practice of my invention are, by way of illustration, inorganic metal, including alkali metal, and amine salts as, for example, sodium, potassium, ammonium, lithium, calcium, magnesium, barium, aluminum, iron, tn'methylamin'e, isopropylamine, ethylamine, diethylamine, triethylamine, tripropylamine, tributylamine, cyclohexylatnine, dicyclohexylamine, 2hydroxyethyla mine, bis-(Z-hydroxyethyl)amine, tris-(2-hydroxyethyl)- amine, beta-hydroxyisopropylamine, bis-(beta-hydroxyisopropyl)amine, propylamine, butylamine, N, N-Di- Inethyl-Z-hydroxyethylamine, N, N-Diethyl-Z-hydroxyethylamine, benzylamine, naphthylamines, triamylamines, dimethylbenzylamine, (dimethyl) (cyclohexyl) amine, methylbenzylamine, piperidine, pyridine, lutidine, morpholine, diphenylamine, Z-phenylethylamine, a-methyl-B hydroxyisopropylamine, and the like.

The following examplesare illustrative of corrosion inhibiting compositions made in accordance with my invention. It will be understood that various changes may be made therein in relation to proportions of the ingreclients and numerous other compositions can readily be evolved in the light of the teachings disclosed herein. Said compositions may be utilized, among other ways, to impregnate carriers or solid bodies of various types to deposit therein the solids comprising the corrosion inhibitingcompositions. All partsgiven are by weight.

Example 1 Sodium nitrite 3O Urea 30 Sodium benzoate 20 Water 60 7 Example 2 Sodium nitrite 6 Urea 12 Ammonium benzoate 10 Water 60 Example 3 Potassium nitrite 10 Acetamide 8 Cyclohexylamine salt of benzoic acid 8 Water 70 Example 4 Sodium nitrite l0 Guanidine 20 Triethanolamine salt of benzoic acid 15 Water 100 Example 5 Ammonium nitrite 5 N-butyl urea 3 Ammonium benzoate 2 Water 2O Exampled Sodium nitrite 10 Urea a 10 Sodium benzoate 5 Ammonium benzoate 3 Water Example 7 Sodium nitrite 11 Urea 11 2-hydroxyethylammonium benzoate 22 Water 1 156 Example 8 iodium nitrite 3 Urea 8 Z-hydroxyethylammonium benzoate 11 Water 78 The three components comprising the corrosion inhibiting compositions which are utilized in accordance with my invention can be employed in varying proportions. Good results are obtained, for example, where, for each part of inorganic nitrite, from 0.05 to 20 parts each of the organic amide and the salt of benzoic acid are employed, said parts being by weight. Especially advantageous results are obtained Where the ingredients are employed in proportions amounting to substantially equal parts of inorganic nitrite and organic amide with a slightly greater proportion of the salt of benzoic acid.

When the corrosion inhibiting composition is embodied or incorporated into a solid carrier or support member as, for example, a sheet of paper, a corrugated or other carton, a separator, or a wrapper or the like, good results are obtained where the corrosion inhibiting composition is present in a concentration of from about 0.1 to or grams per square foot of surface of the carrier sheet or the like. In the usual case, the corrosion inhibiting composition is very effective when it is present in or on the carrier or support member in the total amount of the order of about 2 to 4 grams per square foot of sheet surface area to which the ferrous article to be protected is exposed.

The corrosion inhibiting composition may be incorporated into or upon a suitable carrier, which may be sheet stock, finely divided particles of relatively inert material, and the like, in any one of several ways disclosed, for example, in the aforementioned patent. Thus, all of the ingredients may be dissolved in a suitable solvent, for instance, water, or an organic solvent or a mixture of solvents, and the carrier impregnated with the solution after which the solvent material may be evaporated. Alternatively, the corrosion inhibiting composition may be utilized in the form of a dispersion or emulsion and deposited into or upon a carrier by dipping, brushing, spraying and other ways known in the art. While, in commercial practice, it is desirable that all of the ingredients comprising the corrosion inhibitingcompositions of the present invention be deposited on or into thecarrier from a single solution or dispersion or the like, it will be appreciated that such procedure need not be followed. Thus, for example, the inorganic nitrite may initially be deposited in or upon the carrier after which the organic amide may be deposited followed by the deposition of the salt of benzoic acid, or the order of the deposition of the aforesaid ingredients may be altered in any way desired. The important thing is that all three of said ingredients be present so that they can exert their conjoint effects.

As described in the aforesaid patent, it is frequently desirable to coat one side of a sheet of paper or other absorbent cellulosic or fabric material or the like, which has been impregnated with a corrosion inhibiting composition, with a water-repellent or moisture-proof mate-- rial for the purposes of preventing too rapid dissipation of the corrosion inhibiting composition and to insure against undue moisture absorption by said carriers where one or more of the ingredients of the corrosion inhibiting composition utilized is of a hygroscopic character. A number of water-repellent materials is readily available for use in this connection as, for example, waxes, such as microcrystalline waxes, asphaltums, soaps of normally solid fatty acids such as sodium stearate, and various other materials of this type. For a more detailed description thereof, and for a detailed description of various carriers and manners of utilizing in practical commercial ways corrosion inhibiting compositions of the type here involved, reference may be had to the aforementioned patent and application as well as to the application .of

4 Clemens A. Hutter, Serial No. 124,852, filed November 1, 1949, now Patent No. 2,534,201, dated November 12, 1950. The teachings and practices disclosed in said patent and applications can be and advantageously are utilized in the practice of my present invention.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. A vapor phase inhibiting composition for inhibiting corrosive attack on metal by elements normally existing in the atmosphere comprising, as essential ingredients, an organic amide, an inorganic metal nitrite, and a salt of benzoic acid selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, barium, aluminum and iron, said ingredients being present in the ratio of about 1 part by weight of said nitrite to 0.05-2O parts by weight each of said amide and said salt of benzoic acid.

2. A vapor phase inhibiting composition for inhibiting corrosive attack on metal by elements normally existing in the atmosphere comprising, as essential ingredients, an amide selected from the group consisting of mono-, diand polyamides, a water-soluble metal nitrite, and a salt of benzoic acid selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, barium, aluminum and iron, said ingredients being present in the ratio of about one part by weight of said nitrite to 0.05- parts by weight each of said amide and said benzoic acid salt.

3. A vapor phase inhibiting composition for use in the inhibition of corrosive attack on metal by elements normally existing in the atmosphere comprising, as essential ingredients, an aqueous solution of an amide having less than carbon atoms in chain-like arrangement, an inorganic nitrite, and a salt of benzoic acid selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, barium, aluminum and iron, said ingredients being present in the ratio of 1 part of said nitrite to 0.05-20 parts each of said amide and said benzoic acid salt.

4. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising a solid carrier embodying therein an organic amide, an inorganic nitrite, and a salt of benzoic acid selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, barium, aluminum and iron, said ingredients being present in the ratio of 1 part of said nitrite to 0.03 40 parts each of said amide and said benzoic acid salt.

5. An article of manufacture in accordance with claim 4, in which the carrier is an absorbent cellulosic sheet, and the ingredientswhich are embodied therein are present in a total amount of from about 2 to about 4 grams per square foot of sheet surface area.

6. An article of manufacture in accordance with claim 5, in which one surface of the cellulosic sheet is backed by a layer of moisture-repellent material.

7. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising sheet stock impregnated with a water-soluble amide, a water-soluble inorganic nitrite, and a salt of benzoic acid, selected from the group consisting of sodium, potassium, lithium, calcium, magnesium, barium, aluminum and iron, the amide and the nitrite being present in the sheet stock in approximately equal parts by weight, and the said benzoic acid salt being present in the sheet stock in slightly greater proportions than the amide, the aforesaid ingredients being present in said sheet stock in a total amount of about 2 to about 4 grams per square foot of sheet surface area, one surface of said sheet stock carrying a backing comprising a layer of moisture-repellent material.

8. An article of manufacture for inhibiting the corrosion of metal by means of vapor phase inhibition comprising paper sheet stock impregnated with urea, an alkali metal nitrite, and the sodium salt of benzoic acid, .the

areasvo References Cited in the file of this patent UNITED STATES PATENTS 2,334,158 Fuchs et a1 Nov. 9, 1943 2,504,200 Johansson Apr. 18, 1950 15 2,521,311 Schwoegler et al Sept. 5, 1950 2,629,649 Wachter Feb. 24, 1953 6 FOREIGN PATENTS 600,328 Great Britain Apr. 6, 1948 596,160 Great Britain Dec. 30, 1947 588,864 Great Britain June 7, 1947 OTHER REFERENCES Corrosion Causes and Prevention, by Frank N. Speller, McGraw-Hill Book Co., Inc., N. Y. and London,

0 1951, at page 214.

Vernon, W. H. J.: J. Soc. Chem. Ind., vol. 66, p. 139, May 1947.

Amines Check Corrosion, in Power, March 1951, at p. 71.

Baker et al.: Polar Type Rust Inhibitors, Industrial and Eng. Chem, vol. 40, December 1948, pp. 2338-2347. 

1. A VAPOR PHASE INHIBITING COMPOSITION FOR INHIBITING CORROSIVE ATTACK ON METAL BY ELEMENTS NORMALLY EXISTING IN THE ATMOSPHERE COMPRISING AS ESSENTIAL INGREDIENTS, AN ORGANIC AMIDE, AN INORGANIC METAL NITRITE, AND A SALT OF BENZOIC ACID SELECTED FROM THE GROUP CONSISTING OF SODIUM, POTASSIUM, LITHIUM, CALCIUM, MAGNESIUM, BARIUM, ALUMINUM AND IRON, SAID INGREDIENTS BEING PRESENT IN THE RATIO OF ABOUT 1 PART BY WEIGHT OF SAID NITRITE TO 0.05-20 PARTS BY WEIGHT EACH OF SAID AMIDE AND SAID SALT OF BENZOIC ACID. 